1. Field of the Invention
The present invention relates generally to stator winding and, more particularly, to an apparatus and method for winding coils on stators for dynamo-electric machines, including an improved winding apparatus for providing improved winding speeds.
2. Description of the Prior Art
Field winding coils for stators are generally placed on the radially inwardly extending teeth of a stator by either preforming the coils and then pressing the preformed coils over the stator teeth, or by winding the coils directly onto the stator teeth. In the process where the coils are preformed, the coils are pushed onto the stator by a coil pusher which forcibly pushes the coils over the teeth of the stator, and a forming tool, or forming tools, may be provided to shape the wire in the stator slots and around the ends of the teeth in order to compactly position the coils on the stator. In such a construction, excess wire must be provided for the preformed coils in order to accommodate the necessary distortions of the coils as they are pressed over and around the stator teeth. Accordingly, such a construction has been found to provide an inefficient amount of wire, as well as result in a larger stator dimension as a result of the excess coil wire extending around the end faces of the teeth for the stator.
In the alternative construction for field winding, wire is fed from a winding spindle or tool directly onto a stator wherein the wire is successively wound around the stator teeth, and the efficiency of the winding operation is substantially dependent upon the ability to direct the wire to desired locations on the teeth as it is fed from the winding spindle. Such a device for feeding wire onto the stator to form the coils directly thereon is disclosed in U.S. Pat. No. 5,964,429, which discloses a winding tool which is supported for vertical reciprocating and rotating movement relative to a stator. The winding tool includes a plurality of forming racks which are adapted to move radially outwardly from the winding tool in order to press the end portions of the coil windings radially outwardly and thereby facilitate placement of additional wire within the slots of the stator.
A further winding tool for forming coils directly onto a stator is disclosed in U.S. Pat. No. 6,616,082 which describes a vertical winding machine including a winding tool which moves in reciprocating movement through the stator as wire is fed onto the stator teeth. During movement of the winding tool, a drifting tool is moved into engagement with the wire coils being formed such that a drifting operation is performed simultaneously with movement of the winding tool to place wire around the stator teeth.
There is a continuing need for a winding tool which efficiently winds wire onto stators and which is capable of reducing the winding time through increased apparatus operation speeds.